U.S. patent number 4,913,239 [Application Number 07/357,188] was granted by the patent office on 1990-04-03 for submersible well pump and well completion system.
This patent grant is currently assigned to Otis Engineering Corporation. Invention is credited to Russell I. Bayh, III.
United States Patent |
4,913,239 |
Bayh, III |
April 3, 1990 |
Submersible well pump and well completion system
Abstract
A submersible well pump and downhole completion system. The
system includes a fluid flow path from the well surface to inject
lubricating fluid to increase downhole pump life and/or corrosion
inhibitors to protect downhole components from potentially harmful
well fluids. The system substantially increases the service life of
downhole components used to enhance the production of well fluids.
The system also offers ease of assembly at the well surface and
installation at the desired downhole location.
Inventors: |
Bayh, III; Russell I.
(Carrollton, TX) |
Assignee: |
Otis Engineering Corporation
(Dallas, TX)
|
Family
ID: |
23404646 |
Appl.
No.: |
07/357,188 |
Filed: |
May 26, 1989 |
Current U.S.
Class: |
166/385; 166/105;
166/382; 166/65.1; 166/66.4 |
Current CPC
Class: |
E21B
17/003 (20130101); E21B 23/14 (20130101); E21B
41/02 (20130101); E21B 43/128 (20130101) |
Current International
Class: |
E21B
23/00 (20060101); E21B 43/12 (20060101); E21B
23/14 (20060101); E21B 41/02 (20060101); E21B
41/00 (20060101); E21B 17/00 (20060101); E21B
019/02 (); E21B 034/10 (); E21B 043/12 () |
Field of
Search: |
;166/68,66.4,65.1,104,105,105.5,106,107,382,385 ;174/7R,28,24
;417/360,423.3,423.13 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Completion Capabilities of a New Cable Deployed Electric
Submersible Pumping System for Enhanced Oil Production Petroleum
Society of CIM Paper No. 89-40-13..
|
Primary Examiner: Novosad; Stephen J.
Attorney, Agent or Firm: Felger; Thomas R.
Claims
What is claimed is:
1. A well completion system for a downhole submersible pump and
motor comprising:
a. a production tubing string with a landing nipple forming an
integral part thereof and defining in part a downhole location for
releasably anchoring a submersible pump and related components
within the production tubing string;
b. a power cable having electrical conductors and fluid conductors
to supply both electricity and treating fluid from the well surface
to the submersible pump and related components; and
c. a fluid flow path extending through the submersible pump motor
and its related components to receive treating fluid from the power
cable.
2. A well completion system as defined in claim 1 further
comprising:
a. a downhole electric motor to operate the submersible pump;
b. a cable anchor assembly to electrically and mechanically attach
the power cable to the electric motor;
c. a small diameter conduit extending from the exterior of the
cable anchor assembly to a fluid receiving chamber above the
electric motor; and
d. the small diameter conduit supplying treating fluid from the
power cable to the fluid flow path.
3. A well completion system as defined in claim 2 wherein the fluid
flow path further comprises:
a. the fluid receiving chamber disposed between the cable anchor
assembly and the electric motor;
b. an opening from the fluid receiving chamber into the electric
motor to communicate treating fluid therebetween; and
c. a plurality of relief valves to allow treating fluid to exit
from the interior of the electric motor and its related
components.
4. A well completion system as defined in claim 1 further
comprising:
a. an electric motor for the submersible pump;
b. a cable anchor assembly to mechanically attach the power cable
to the electric motor and other related components of the
submersible pump;
c. a fluid receiving chamber below the cable anchor assembly;
d. a small diameter conduit extending from the exterior of the
cable anchor assembly to the fluid receiving chamber to supply
treating fluid from the power cable to the chamber;
e. separate cylindrical housings generally defining the exterior of
the electric motor and each related component;
f. an opening from the fluid receiving chamber into the electric
motor to communicate treating fluid therebetween;
g. similar openings between other components of the electric motor
to communicate treating fluid therebetween; and
h. a relief valve extending through each housing to allow treating
fluid to exit from the interior of the respective housing.
5. A well completion system as defined in claim 1 wherein the
treating fluid is selected from the group consisting of mineral
oil, di-electric fluid, lubricating oil, and corrosion
inhibitor.
6. The method of installing and operating a downhole submersible
pump and motor comprising:
a. attaching the submersible pump with its motor and related
components to a power cable having electrical conductors and a
fluid conductor to supply both electricity and treating fluid from
the well surface to the submersible pump motor and related
components;
b. lowering the submersible pump, motor and related components by
the power cable through a production tubing string to a landing
nipple which defines in part a downhole location for releasably
anchoring the submersible pump and related components within the
production tubing string; and
c. injecting treating fluid from the well surface through the power
cable to a fluid flow path extending through the submersible pump
motor and its related components.
7. The method of claim 6 further comprising the step of maintaining
treating fluid within the submersible pump motor and its related
components at a pressure higher than the pressure of well fluids
surrounding the exterior of the submersible pump motor and its
related components.
8. The method of claim 7 further comprising the step of maintaining
treating fluid pressure within the submersible pump motor and its
related components above well fluid pressure by a plurality of
spring loaded, relief valves which allow treating fluid to exit
from the submersible pump motor and its related components and
block well fluids from flowing therein.
9. The method of claim 6 further comprising the step of injecting
treating fluid from the well surface into the pump motor and its
related components before supplying electrical power to the pump
motor.
10. The method of claim 6 further comprising the step of
maintaining a constant bath of lubricating oil within selected
portions of the submersible pump motor.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to submersible well pumps and particularly
to increasing the downhole service life of the pump motor and
related equipment.
2. Description of the Relevant Art
Submersible pumps have been installed at preselected downhole
locations in well bores by various well completion systems and
techniques. Some examples include:
attaching the pump to the production tubing string as shown In U.S.
Pat. Nos. 4,502,536 and 4,589,482;
suspending the pump from its power cable as shown in U.S. Pat. Nos.
4,128,127 and 4,363,359;
supporting the pump on a well packer or similar downhole resting
place as shown in U.S. Pat. No. 4,625,798; or
releasably anchoring the pump in a downhole landing nipple as shown
in U.S. Pat. No. 4,749,341;
The present invention resulted from design, manufacture, and
testing of equipment shown in U.S. Pat. No. 4,749,341. The
preferred power cable for use with the present invention is shown
in U.S. Pat. No. 4,740,658. Other power cables could be modified
for use with the present invention such as the cable shown in U.S.
Pat. No. 4,716,260.
The preceding patents are incorporated by reference for all
purposes within this application.
SUMMARY OF THE INVENTION
The present invention discloses a well completion with a
submersible pump and power cable. In addition to electrical energy
to operate the pump, the power cable also supplies fluid to
lubricate and/or protect the pump motor and related downhole
components from potentially harmful well fluids. The pump, its
prime mover (an electric motor), and related components have a flow
path to receive fluids such as lubricating oil, corrosion
inhibitor, purge fluids, etc. from the well surface. The power
cable is used to install and remove the pump and related components
from a selected downhole location defined in part by a landing
nipple.
An object of this invention is to provide a method and system for
releasably anchoring a submersible pump with its power cable at a
downhole location in a well bore defined in part by a landing
nipple in a production tubing string. The power cable extends
upwardly and if desired may be placed in tension above the pump to
prevent damage to the cable.
Another object is to provide a locking module assembly and
discharge head with a collet, which releasably engages a groove or
grooves in a landing nipple. The collet is more difficult to pull
out of the groove than to insert into the landing nipple, so that
the cable may be placed in tension if desired to protect the cable
from damage without releasing the locking module assembly.
Another object is to provide a locking module assembly for
supporting a pump in which the locking module assembly is
releasably latched against relative rotation and a cable anchor
assembly which connects the power cable to an electric motor in a
manner to prevent relative rotation between the cable and motor.
The cable anchor assembly prevents damage to electrical and fluid
conductors which are positioned exterior to and extend from the
power cable to the motor.
Another object is to provide fluid coductors and a fluid flow path
to direct fluid from the well surface via the power cable to the
pump motor and related downhole components. Fluid from the well
surface may be used to:
lubricate the downhole equipment;
purge well fluids from the downhole equipment; and/or
inject corrosion inhibitor to protect the downhole equipment and
production tubing string from potentially harmful well fluids.
Additional objects and advantages of the invention will be readily
apparent to those skilled in the art from reading the following
description in conjunction with the drawings and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view, partially in longitudinal section and
partially in elevation, showing a well completion with a
submersible pump and related downhole equipment incorporating the
present invention.
FIGS. 2A through 2F are continuation drawings, partially in
elevation and partially in longitudinal section with portions
broken away, illustrating a power cable, cable anchor assembly,
electrical connections, electric motor, locking module assembly,
pump discharge head, and pump with the fluid flow path(s) of the
present invention.
FIGS. 3A and 3B are enlarged continuation drawings, partially in
elevation and partially in longitudinal section with portions
broken away, illustrating the cable anchor assembly and electrical
connector means of FIG. 2A in more detail.
FIG. 4 is a drawing in horizontal sectional taken along the lines
4--4 of FIG. 3A.
FIG. 5 is a drawing in horizontal sectional taken along the lines
5--5 of FIG. 3A.
FIG. 6 is a drawing in horizontal sectional taken along the lines
6--6 of FIG. 3A.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention will be described with respect to electric
submersible pumps. However, the principal features of the invention
(lubrication of moving components, protection of downhole
components from potentially harmful well fluids, ease of assembly
and installation) could be used with other downhole submersible
pumps. Examples of such pumps include hydraulically powered turbine
pumps, hydraulically powered reciprocating pumps, and mechanically
powered pumps.
FIG. 1 shows a portion of a well completion which includes
production tubing string 20 and landing nipple 21 as an integral
part thereof. Production tubing string 20 will typically be
concentrically disposed within a casing string (not shown). A
typical casing string essentially defines the well bore and extends
from a wellhead and Christmas tree (not shown) at the well surface
to an underground hydrocarbon producing formation (not shown).
Perforations (not shown) extend through the casing to allow fluid
communication between the interior of the casing and the
hydrocarbon producing formation adjacent thereto. A production well
packer (not shown) is typically installed in the casing string
above the perforations to direct well fluid flow from the
hydrocarbon producing formation to the well surface via production
tubing string 20. Surface controlled subsurface safety valves,
additional well packers, and other flow control devices may be
included as an integral part of tubing string 20. Examples of such
well completions with a wide variety of available downhole
equipment are shown in more detail in U.S. Pat. Nos. 4,625,798 and
4,749,341.
Landing nipple 21 partially defines the downhole location for
releasably anchoring submersible pump 70 and related components
within the well bore. Submersible pump 70 and its prime mover
(electric motor 50) are suspended from power cable 30 within tubing
string 20. Power cable 30 is preferably a multiconductor multiwire
rope cable which can supply both electrical power and fluid from
the well surface to submersible pump 70 and electric motor 50.
Power cable 30 can also be used to insert and retrieve submersible
pump 70, electric motor 50, and related components from the
selected downhole location.
Threads 71 are provided on the extreme lower end of pump 70 to
attach additional downhole tools thereto. Examples of such tools
include subsurface safety valves, seal units, and inlet piping.
Ports 25 are shown in tubing 20 below landing nipple 21 to allow
gas to exit from tubing 21 without having to flow through pump
70.
Major components associated with and related to electric motor 50
and submersible pump 70 include cable anchor assembly 40,
electrical connector means 45, and locking module assembly 60.
Cable anchor assembly 40 and electrical connector means 45 are
provided to mechanically and electrically connect submersible pump
70, electric motor 50, and related components to power cable 30.
Locking module assembly 60 can be releasably engaged with landing
nipple 21. Locking module assembly 60 also provides discharge head
61 with a plurality of discharge ports 62 to direct well fluid
discharged from pump 70 to the well surface via tubing 20. Each of
these components will be discussed in more detail.
Cable anchor assembly 40 is shown in FIGS. 1, 2A and 3A. Power
cable 30 preferably includes two wire ropes 31 and 32 which can be
securely engaged with cable anchor assembly 40 as taught by U.S.
Pat. No. 4,749,341. Drum sockets (not shown) or helical splice rod
terminations as shown in FIG. 2A are well known means for securing
wire ropes 31 and 32 within cable anchor assembly 40.
Cable anchor assembly 40 has two major subassemblies tubular
housing 41 and solid mandrel 42. Tubular housing 41 is a generally
hollow, cylindrical sleeve sized to fit over the terminal end of
power cable 30. Solid mandrel 42 is securely locked into the end of
tubular housing 41 opposite from power cable 30. Various types of
threaded connections and locking rings or set screws (not shown)
may be used to satisfactorily engage housing 41 with mandrel 42.
Preferably, the connections of power cable 30 within housing 41 and
housing 41 to mandrel 42 are keyed to prevent relative rotation
between these items.
Window (longitudinal slot) 43 is machined through the exterior of
tubular housing 41 intermediate the ends there. Power cable 30
preferably includes three electrical conductors 88, 89 and 90 plus
fluid line 100 which extend through window 43 to components
therebelow. Fluid line 100 is a relatively small diameter conduit
similar to control fluid lines associated with surface controlled
subsurface safety valves.
Electrical connector means 45 includes general cylindrical, hollow
sleeve 46 which is mechanically attached to solid mandrel 42 by
locking rings 37 and 38 by set screws 39. A similar mechanical
connection can be used to attach tubular housing 41 to solid
mandrel 42. FIGS. 3A and 3B show details concerning the internal
design of electrical connector means 45 and will be discussed later
in more detail.
Electrical energy from power cable 30 is supplied via conductors
88, 89 and 90 through electrical connector means 45 to electrical
motor 50. Armature and stator windings 51 and 52 respectively
rotate shaft 53 in response to the electrical energy supplied by
power cable 50. FIGS. 2B and 2C show a typical electrical induction
three-phase AC downhole motor used as the prime mover for
centrifugal pump 70. Shaft 53 is rotatably connected to pump 70 by
several splined connections 54. Shaft 53 is supported by both
thrust bearings such as shown at 55 in FIG. 2B and radial bearing
as shown at 56 in FIGS. 2D. The number, type, and location of
bearings can be varied depending upon the requirements of downhole
motor 50 and submersible pump 70. Radial bearing 56 also includes a
fluid seal or barrier to prevent undesired fluid flow along the
exterior of shaft 53. FLuid line 100, an important feature of the
present invention, allows various fluids to be injected from the
well surface via power cable 30 to protect bearings 55 and 56 and
other critical components in motor 50.
Locking module assembly 60 performs three critical functions with
respect to the well completion system for downhole submersible pump
70 and its associated components. These functions are partially
supporting the weight of pump 70 and associated components,
directing fluid flow and protecting power cable 30.
A plurality of flexible collet fingers 121 are provided on the
exterior of locking module assembly 60 to releasably engage groove
or recess 122 on the interior of landing nipple 21. Engagement of
collet fingers 121 with groove 122 allows a selected amount of
upward tension to be placed on power cable 30 without releasing
locking module assembly 60 from landing nipple 21. The amount of
tension (if any) is a function of the well head connection (not
shown) for power cable 30 and the weight of the downhole
components.
Fluid seals 119 on the exterior of locking module assembly 60
engage smooth bore 23 of landing nipple 21 to prevent undesired
fluid flow around the exterior of locking module assembly 60. Fluid
seals 119 block formation fluids exiting from discharge ports 62
from flowing downwardly towards the inlet for pump 70. Fluid seals
119 ensure the formation fluids exiting from discharge ports 62
flow upwardly within production tubing 20 to the well surface.
No-go shoulder 111 on the interior of landing nipple 21 and
matching no-go shoulder 63 on the exterior of locking module
assembly 60 cooperate to support the weight of pump 70 and
associated components such as motor 50. The amount of weight
depends upon the tension (if any) placed in power cable 30. No-go
shoulders 111 and 63 are positioned relative to collet fingers 121
and groove 122 to allow engagement of collet fingers 121 in groove
122 before shoulders 111 and 63 contact each other. The
distribution of weight supported by power cable 30 and no-go
shoulders 111 and 63 depends upon several factors such as depth of
landing nipple 21, fluid pressure exiting discharge ports 62 as
compared to pump inlet pressure, weight of pump 70, motor 50, and
inlet piping (if any) attached to pump 70.
By installing locking module assembly 60 in place against an upward
force below a selected amount, power cable 30 may be placed in
tension at the well surface. This tension will prevent damage to
cable 30 from possible bending at its attachment with cable anchor
assembly 40.
Hollow, tubular sleeve 47 is engaged below electrical connector
means 45 to provide fluid receiving chamber 48. Sleeve 47 also
provides part of the mechanical connection between electrical motor
50, cable anchor assembly 40 and electrical connector means 45.
Fluid line 100 from power cable 30 is connected to chamber 48 by
threaded fitting 101. Fluid receiving chamber 48 is part of a fluid
flow path which extends through electrical motor 50 and its related
components. The fluid flow path receives treating fluid such as
lubricating oil, mineral oil based lubricants, corrosion inhibitor
or di-electric fluids from power cable 30 via fluid line 100. The
fluid flow path can be used to purge harmful well fluids from the
interior of motor 50 and to provide a constant bath to protect
critical bearings and fluid seals. A suitable opening such as
passageway 57 is provided between the various sections of
electrical motor 50 to communicate treating fluid from chamber 48
therewith. Passageway 57 extends from receiving chamber 48 into
motor 50 around the upper end of shaft 53.
A plurality of relief valves such as shown at 80, 81, and 82 are
threaded into electric motor 50 and its related components to allow
treating fluid to exit therefrom. Electric motor 50 and its related
components are defined in part by separate cylindrical housings
such as 58 and 59. Preferably, relief valve 80, the closest to
fluid receiving chamber 48, will have the highest setting pressure.
Each relief valve, below valve 80, will have an incrementally lower
setting pressure. Thus, as treating fluid is introduced into motor
50, the fluid will exit from the lower valve first. Therefore, the
relief valves below valve 80 serve as purge valves to remove
undesired fluids from within motor 50.
Power cable 30 includes wire ropes 31 and 32 on either side of
multiple electrical conductors 88, 89 and 90 and fluid line 100.
The electrical conductors, wire ropes and fluid line are contained
within an envelope of relatively stiff but flexible material 91.
The cable is available from The Kerite Comapny, Seymour,
Connecticut. Preferably, at least one side of power cable 30 at its
lower end has a pair of flats which may be engaged to prevent
rotation between cable anchor assembly 40 and power cable 30. FIG.
2A shows power cable 30 with envelope 91 stripped away from its
lower end, leaving bare the electrical conductors and wire ropes 31
and 32.
FIGS. 2D and 2E illustrate landing nipple 21 with an upwardly
facing no-go shoulder 111, against which locking module assembly 60
rests. Below no-go shoulder 111, a smooth bore 23 provides a seal
area. Below the seal area, an enlarged wall section provides land
113 (reduced inside diameter) which terminates at its lower end in
downwardly facing beveled shoulder 114 for engagement by collet
fingers 121.
Locking module assembly 60 is provided with a sealing system
indicated generally at 119. A plurality of collet fingers 121 are
provided on the exterior of locking module assembly 60 below seals
119. Collet fingers 121 are supported at both their top and bottom
ends. Collet heads 123 are formed by an enlarged outside diameter
portion intermediate the ends of collet fingers 121. Collet heads
123 are sized to be received in groove 122 of landing nipple 21.
Collet heads 123 engage land 113 during the installation of
submersible pump 70 in production tubing 20. After collet heads 123
pass shoulder 114, they snap into the position shown in FIG. 2E and
resist upward movement of locking module assembly 60. The surface
angles on the exterior of collet heads 123 are selected to permit
easy insertion of locking module assembly 60 into landing nipple 21
and more difficult withdrawal. For instance, it is preferred that
less than one thousand pounds of force be required to move locking
module assembly 60 downhole to the position shown in FIGS. 2D and
2E and collapse collet fingers 121 as they move past land 113.
Seal bore 23 has a substantial length and the lower end of the
seals 119 preferably engage bore 23 prior to collet fingers 121
engaging land 113. Thus, if a problem is encountered in moving
locking module assembly 60 downwardly to its latched position,
tubing 20 may be pressurized and the pressure above locking module
assembly 60 utilized to force it downwardly and latch collet
fingers 121 in place. It is preferred that a substantial force be
required to move locking module assembly 60 upwardly and compress
collet fingers 121. This upward force should be at least
approximately five thousand pounds and preferably on the order of
ten thousand pounds. By providing a resistance to upward movement
of at least approximately five thousand pounds cable 30 may be
placed in substantial tension and avoid prior art problems of cable
failure adjacent to cable anchor assembly 40.
Locking module assembly 60 (FIG. 2C) includes a key 124 which is
urged outwardly by spring 125 into slot 126 in landing nipple 21.
More than one slot 126 may be provided. This prevents rotation of
pump 70 and related components when motor 50 is operating. If key
124 and slot 126 are not in register when locking module assembly
60 is installed, the reaction force from rotation of armature 51 in
motor 50 will rotate locking module assembly 60 until key 124
registers with a slot 126, at which time key 124 will expand and
engage to prevent further rotation of locking module assembly
60.
Electrical Connections
Electrical connector means 45 provides both a mechanical link
between cable anchor assembly 40 and locking module assembly 60 and
an electrical link between power cable 30 and electric motor 50.
Electrical conductors 88, 89, and 90 exit from window 43 and enter
slot 132 machined in the lower end of solid mandrel 42. Slot 132
protects conductors 88, 89, and 90.
Three electrical penetrators 128, 129 and 130 are disposed within
hollow sleeve 46 for electrical engagement with conductors 88, 89
and 90 respectively. Each penetrator 128, 129 and 130 has a
plurality of o-ring seals such as shown at 94 and 95 to block
undesired fluid flow into electrical connector means 45.
The various components of the downhole completion are held in
alignment and against rotation either by a fully made up threaded
joints between various sections or by keys, set screws and the like
so that, once fully assembled, no relative rotation is possible
between the motor 50, pump 70, and cable 30 to protect electrical
conductors 88, 89 and 90 between cable 30 and motor 50.
The previous description and drawings illustrate only one
embodiment of the present invention. Alternative embodiments will
be readily apparent to those skilled in the art without departing
for the spirit and scope of the invention as defined by the
claims.
* * * * *